Monitoring food and health news -- with particular attention to fads, fallacies and the "obesity" war

Summary of findings to date: Everything you can possibly eat or drink is both bad and good for you

"Let me have men about me that are fat... Yond Cassius has a lean and hungry look ... such men are dangerous." -- Shakespeare

Wednesday, December 13, 2006

Physical activity can curb many a cancer

The above heading is original to the article below but is deceptive. See why at the foot of the article

Health promotion campaigns have helped the Australian public become increasingly aware of the benefits of physical activity and exercise for improving or maintaining health. Most messages are focused on the importance of exercise for the prevention and management of conditions such as heart disease or diabetes. Surprisingly, little is mentioned of the significant impact of exercise on the nation's leading cause of death - cancer. Furthermore, cancer sufferers themselves may not be aware of the mounting evidence that physical activity significantly improves survival rate.

The lifetime risk of cancer for Australians is one in three for males and one in four for females. With 88,000 new cases diagnosed each year, it accounts for 30 per cent of all male and 25 per cent of all female deaths. Prostate cancer is the most common cancer in men, followed by lung and colon. For women, breast cancer is the most common, followed by lung and colorectal.

There is growing evidence that a number of lifestyle factors contribute to the much higher incidence of cancer in developed nations such as Australia - particularly physical inactivity, low consumption of fibre and folate, and a high consumption of saturated fats and red meat. While physical activity reduces the risk of developing various cancers, obesity has been linked to an increased risk of cancer, as well as poorer survival rates (Cancer 2006;107(3):632).

However, growing evidence supports physical activity not only for prevention of cancer, but for significantly improving survival rates. A study published last year in the Journal of the American Medical Association involving 2987 women diagnosed with breast cancer rocked the scientific community when it revealed that walking 3-5 hours per week reduced the risk of dying from the cancer by 40 per cent (2005;293(20):2479).

The growing body of research was added to this year with two separate studies on colorectal cancer in the Journal of Clinical Oncology (2006;24:3527 and 2006;24:3535). Both investigated the association between physical activity undertaken after diagnosis and its relationship with survival, and found that there was a 50-60 per cent reduction in both the recurrence of the cancer and overall mortality compared to those who were sedentary.

These results have significant implications for cancer therapy, as bowel cancer is the most frequently occurring internal cancer with more than 13,000 people diagnosed each year. An aggressive cancer, only 56 per cent of people with the condition survive five years after diagnosis.

Although the physiological effects of exercise on cancer survival are not yet understood, there are various proposed mechanisms including improved hormone regulation, decreases in blood insulin levels, enhanced anti-tumour immune function and a decrease in free-radicals. Regardless of the mechanism, what is certain is that it does have a positive impact, and there are calls for greater promotion of physical activity and exercise for both prevention and treatment.

A study published in the Health Promotion Journal of Australia last year revealed that two in three people were motivated to increase their physical activity if they believed it could reduce their risk of bowel cancer. Based on these findings, it would be reasonable to assume that cancer sufferers informed of the research linking exercise to improved survival rates would be motivated to a greater extent to increase their physical activity. However, the study's author, doctor Geoffrey Jalleh, claimed that cancer organisations did not actively promote the protective effects of physical activity on common cancers including bowel and breast. "As a result, the general public's awareness of the links between physical inactivity and increased risk for cancer is minimal."

What is clear is that if physical activity can have a similar effect as trastuzumab - an agent for the treatment of breast cancer, and sold under the brand name Herceptin - then exercise needs to undergo an investigative process similar to the development of a medication. Further research is needed to determine the optimal dose of exercise for each type of cancer, the ideal type of activity (strength training versus cardiovascular exercise), and potential side effects.

Preliminary data shows that exercise reduces the side effects associated with cancer treatment, and is quite safe as a treatment modality (Support Cancer Care 2006;14:732). However, in a recent review, a major barrier identified to promoting physical activity in cancer patients is the confidence level of the treating oncologist to provide their patient with appropriate exercise advice. Considering that this review was conducted in the US, this problem may be overcome in Australia through a partnership-based approach between the oncologist and exercise physiologist, providing the basis for better health outcomes and greater research.

As leading cancer and exercise researcher Demark-Wahnefried recently stated in the Journal of Oncology: "There is no doubt that the pharmaceutical industry would back an agent with potential to reduce cancer recurrence by at least 50 per cent, but who will back a trial that evaluates the potential benefits of sneakers and sweatpants?"

The author above is Chris Tzar, an exercise physiologist and director of the Lifestyle Clinic, Faculty of Medicine, University of NSW, so an excess of enthusiasm for his chosen field can perhaps be forgiven. He gives the impression above that exercise can prevent all sorts of cancers. That is not true. All the studies he notes above refer to people who ALREADY HAVE cancer, a population that is by definition different from the population as a whole.

There is however other evidence on whether exercise prevents cancer and it shows good evidence for benefit in the case of colon cancer only. Even rectal cancer occurrence is unrelated to exercise. There is also some evidence that exercise is a preventive for breast cancer in women -- but so is being fat a preventive for breast cancer in women. So a woman who has a family history of breast cancer would be at least as well advised to eat plenty of Big Macs and KFC as to exercise. I think I can say with absolute certainty, however, that you would never hear that advice from Mr Tzar, correct though it is. That would be completely against the prevailing religion. He is good at hinting at bias in others (see his last sentence above) but I doubt that he sees his own biases as any problem.

Clearly however, men with a family history of colon cancer should exercise as long as they do not have counterindications for it as well

Low fat warning

Dieters who use low-fat foods to try to cut their weight can consume up to 45% more calories than they intend, researchers have found, writes Jonathan Leake. They warn that such foods can make people put on weight, because the fats are replaced with sugars or other nutrients that contain nearly as many calories as the original version. Additionally, it is the fats in a food that create a feeling of fullness, so their absence can encourage people to keep on eating even more than they normally would.

"People don't realise that low-fat foods are not always low-calorie foods," said Brian Wansink, professor of marketing and nutritional science at Cornell University in New York, who carried out the research. "Fat is often replaced with sugar. Low-fat snacks are an average of 11% lower in calories, but people wrongly believe they are 40% lower." He found that when offered low-fat snacks rather than regular ones obese people ate up to 45% more calories.

Shoppers are continuing to pile their trolleys and baskets with unhealthy food, despite the Government's focus on tackling Britain's obesity crisis. A survey of food-buying patterns of 12 million consumers has found that, in the past four years, 44 per cent of people have made no change to their eating habits. Only 8 per cent of shoppers have moved towards a healthier diet, while almost as many are deliberately shunning a good diet and eating more junk food. Even shoppers who normally try to eat healthily fall off the wagon if there is an upheaval in their lives such as the arrival of a new baby, divorce, a wedding, moving house, losing a job or being promoted at work.

The findings, from dunnhumby, the retail consultants, who have scrutinised the sales data of 10,000 everyday ingredients clocked up on Tesco loyalty cards as well as interviewed 2,000 customers, suggest that it will take more than a generation before Britain becomes a nation of healthy eaters. The findings will come as a blow to the efforts of Caroline Flint, the Public Health Minister, and the Food Standards Agency, who are attempting to encourage people to eat a more nutritious diet.

The study also appears to suggest that consumers need the help of the agency's traffic-light system of red, amber and green alerts on packs to help them to choose a healthier mix of food. The traffic lights are being strongly opposed by food manufacturers and Tesco, who claim that the system is simplistic and demonises food.

A surprising feature of the study is that there is little difference in the cost of a healthy shopping basket and an unhealthy one. A typical healthy basket costs an average 71.78 pounds compared with 71.18 pounds for an unhealthy one. Healthy shoppers were identified for buying organic and ecofriendly products and food with labels such as fresh, lite or low fat, or food from the healthy-living ranges. [The mugs who believe anything, in other words]

Unhealthy baskets typically contained value or extra lines, indicating that people were looking for the cheapest food that they could find. It suggests that many shoppers still think that healthy eating is expensive. But shoppers also enjoy a treat, and sales of chocolate and alcoholic drinks have shown no decline. They also like to "scrimp and splurge". Researchers identified people who chose cheaper products to pay for a treat, either a cream cake, gourmet food for a pet or a DVD.

Martin Hayward, director of consumer strategy for dunnhumby, said: "Most of us are neither totally healthy nor totally unhealthy eaters." He said that worry about the cost of food prevented many people from eating healthily and yet the analysis had shown that there was little difference in the price of a healthy versus unhealthy basket. Mr Hayward said: "We believe the distance between healthy and unhealthy eating is because people don't know how to cook and have a `can't cook, won't cook' approach, making them heavily reliant on processed foods and ready meals."

The findings are intended to explore new ways to help consumers to eat a healthy diet, he said. The analysis also bolsters policy statements from Tony Blair and David Cameron, the Conservative leader, who have promised to bring cookery classes back into schools.

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter? It is just about pure fat. Surely it should be treated as contraband in kids' lunchboxes! [/sarcasm].

9). For a summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and no lasting harm from them has ever been shown.

Where it is not bunk is when it shows that some treatment or influence has no effect on lifespan or disease incidence. It is as convincing as disproof as it is unconvincing as proof. Think about it. As Einstein said: No amount of experimentation can ever prove me right; a single experiment can prove me wrong.

Epidemiological studies are useful for hypothesis-generating or for hypothesis-testing of theories already examined in experimental work but they do not enable causative inferences by themselves

The standard of reasoning that one commonly finds in epidemiological journal articles is akin to the following false syllogism:
Chairs have legs
You have legs
So therefore you are a chair

I am rather in despair that important medical research is plagued by arrant nonsense. The simple truth that correlation is not causation seems unknown to most medical writers. As a last ditch attempt to get that truth into a few more skulls let me be "offensive". Offensiveness may serve to get the matter noticed. So here is the story: There is about a -.5 correlation between lip size and IQ. Big lips predict low IQ. Your run-of-the mill medical researcher will pounce on that as a huge breakthrough in finding the causes of IQ -- and propound new theories about things such as blood circulation to explain how lips affect IQ. But that is nonsense. Big lips are mostly found on people of African ancestry and, as all the studies attest, Africans are a very low IQ group. The correlation arises because of heredity, not lip size. There is a third factor behind the correlation -- and the possibility of such third factors seems to be a jaw-dropping surprise to most medical researchers

SALT -- SALT -- SALT

1). A good example of an epidemiological disproof concerns the dreaded salt (NaCl). We are constantly told that we eat too much salt for good health and must cut back our consumption of it. Yet there is one nation that consumes huge amounts of salt. So do they all die young there? Quite the reverse: Japan has the world's highest concentration of centenarians. Taste Japan's favourite sauce -- soy sauce -- if you want to understand Japanese salt consumption. It's almost solid salt.

2). We need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. So the conventional wisdom is not only wrong. It is positively harmful

3). Table salt is a major source of iodine, which is why salt is normally "iodized" by official decree. Cutting back salt consumption runs the risk of iodine deficiency, with its huge adverse health impacts -- goiter, mental retardation etc. GIVE YOUR BABY PLENTY OF SALTY FOODS -- unless you want to turn it into a cretin

4). Our blood has roughly the same concentration of salt as sea-water so claims that the body cannot handle high levels of salt were always absurd

5). The latest academic study shows that LOW salt in your blood is most likely to lead to heart attacks. See JAMA. 2011;305(17):1777-1785. More here and here and here for similar findings. Salt is harmless but a deficiency of it is not. We need it. See also here

PEANUTS: There is a vaccination against peanut allergy -- peanuts themselves. Give peanut products (e.g. peanut butter -- or the original "Bamba" if you have Israeli contacts) to your baby as soon as it begins to take solid foods and that should immunize it for life. See here and here (scroll down). It's also likely that a mother who eats peanuts while she is lactating may confer some protection on her baby. See here

THE SIDE-EFFECT MANIA. If a drug is shown to have troublesome side-effects, there are always calls for it to be banned or not authorized for use in the first place. But that is insane. ALL drugs have side effects. Even aspirin causes stomach bleeding, for instance -- and paracetamol (acetaminophen) can wreck your liver. If a drug has no side effects, it will have no main effects either. If you want a side-effect-free drug, take a homeopathic remedy. They're just water.

Although I am an atheist, I have never wavered from my view that the New Testament is the best guide to living and I still enjoy reading it. Here is what the apostle Paul says about vegetarians: "For one believeth that he may eat all things: another, who is weak, eateth herbs. Let not him that eateth despise him that eateth not; and let not him which eateth not judge him that eateth." (Romans 14: 2.3). What perfect advice! That is real tolerance: Very different from the dogmatism of the food freaks. Interesting that vegetarianism is such an old compulsion, though.

Even if we concede that getting fat shortens your life, what right has anybody got to question someone's decision to accept that tradeoff for themselves? Such a decision could be just one version of the old idea that it is best to have a short life but a merry one. Even the Bible is supportive of that thinking. See Ecclesiastes 8:15 and Isaiah 22: 13. To deny the right to make such a personal decision is plainly Fascistic.

Obesity does NOT causes diabetes. But insatiable eating is a prominent symptom of diabetes. So diabetes DOES cause obesity, which accounts for the correlation between the two things. The streets are full of fatties who don't have diabetes. How come? If conventional medical theory were correct we should be in the midst of an epidemic of diabetes. A recent high quality study has also found that fatties are LESS likely to die of diabetes

Elite people frequently express disapproval of red meat eating as a way of expressing their felt superiority to the ordinary people who eat it

IQ: Political correctness makes IQ generally unmentionable so it is rarely controlled for in epidemiological studies. This is extremely regrettable as it tends to vitiate findings that do not control for it. When it is examined, it is routinely found to have pervasive effects. We read, for instance, that "The mother's IQ was more highly predictive of breastfeeding status than were her race, education, age, poverty status, smoking, the home environment, or the child's birth weight or birth order". So political correctness can render otherwise interesting findings moot

"To kill an error is as good a service as, and sometimes better than, the establishing of a new truth or fact" -- Charles Darwin

"Most men die of their remedies, not of their diseases", said Moliere. That may no longer be true in general but there is still a lot of false medical "wisdom" around that does harm to various degrees -- the statin and antioxidant fads, for instance. And showing its falsity is rarely the problem. The problem is getting people -- medical researchers in particular -- to abandon their preconceptions

Bertrand Russell could have been talking about today's conventional dietary "wisdom" when he said: "The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd; indeed in view of the silliness of the majority of mankind, a widespread belief is more likely to be foolish than sensible.”

The challenge, as John Maynard Keynes knew, "lies not so much in developing new ideas as in escaping from old ones".

"Obesity" is 77% genetic. So trying to make fatties slim is punishing them for the way they were born. That sort of thing is furiously condemned in relation to homosexuals so why is it OK for fatties?

****************

Some more problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize dietary fat. But Eskimos living on their traditional diet eat huge amounts of fat with no apparent ill-effects. At any given age they in fact have an exceptionally LOW incidence of cardiovascular disease. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

9). And how odd it is that we never hear of the huge American study which showed that women who eat lots of veggies have an INCREASED risk of stomach cancer? So the official recommendation to eat five lots of veggies every day might just be creating lots of cancer for the future! It's as plausible (i.e. not very) as all the other dietary "wisdom" we read about fat etc.

10). And will "this generation of Western children be the first in history to lead shorter lives than their parents did"? This is another anti-fat scare that emanates from a much-cited editorial in a prominent medical journal that said so. Yet this editorial offered no statistical basis for its opinion -- an opinion that flies directly in the face of the available evidence.

11). A major cause of increasing obesity is certainly the campaign against it -- as dieting usually makes people FATTER. If there were any sincerity to the obesity warriors, they would ban all diet advertising and otherwise shut up about it. Re-authorizing now-banned school playground activities and school outings would help too. But it is so much easier to blame obesity on the evil "multinationals" than it is to blame it on your own restrictions on the natural activities of kids

12. Fascism: "What we should be doing is monitoring children from birth so we can detect any deviations from the norm at an early stage and action can be taken". Who said that? Joe Stalin? Adolf Hitler? Orwell's "Big Brother"? The Spanish Inquisition? Generalissimo Francisco Franco Bahamonde? None of those. It was Dr Colin Waine, chairman of Britain's National Obesity Forum. What a fine fellow!

*********************

Trans fats: For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.

The "antioxidant" religion: The experimental evidence is that antioxidants SHORTEN your life, if anything. Studies here and here and here and here and here and here and here and here, for instance. That they are of benefit is a great theory but it is one that has been coshed by reality plenty of times.

The medical consensus is often wrong. The best known wrongheaded medical orthodoxy is that stomach ulcers could not be caused by bacteria because the stomach is so acidic. Disproof of that view first appeared in 1875 (Yes. 1875) but the falsity of the view was not widely recognized until 1990. Only heroic efforts finally overturned the consensus and led to a cure for stomach ulcers. See
here and here and here.

Dieticians are just modern-day witch-doctors. There is no undergirding in double-blind studies for their usual recommendations

The fragility of current medical wisdom: Would you believe that even Old Testament wisdom can sometimes trump medical wisdom? Note this quote: "Spiess discussed Swedish research on cardiac patients that compared Jehovah's Witnesses who refused blood transfusions to patients with similar disease progression during open-heart surgery. The research found those who refused transfusions had noticeably better survival rates.

Medical wisdom can in fact fly in the face of the known facts. How often do we hear reverent praise for the Mediterranean diet? Yet both Australians and Japanese live longer than Greeks and Italians, despite having very different diets. The traditional Australian diet is in fact about as opposite to the Mediterranean diet as you can get. The reverence for the Mediterranean diet can only be understood therefore as some sort of Anglo-Saxon cultural cringe. It is quite brainless. Why are not the Australian and Japanese diets extolled if health is the matter at issue?

Since many of my posts here make severe criticisms of medical research, I should perhaps point out that I am also a severe critic of much research in my own field of psychology. See here and here

This is NOT an "alternative medicine" site. Perhaps the only (weak) excuse for the poorly substantiated claims that often appear in the medical literature is the even poorer level of substantiation offered in the "alternative" literature.

I used to teach social statistics in a major Australian university and I find medical statistics pretty obfuscatory. They seem uniformly designed to make mountains out of molehills. Many times in the academic literature I have excoriated my colleagues in psychology and sociology for going ga-ga over very weak correlations but what I find in the medical literature makes the findings in the social sciences look positively muscular. In fact, medical findings are almost never reported as correlations -- because to do so would exhibit how laughably trivial they generally are. If (say) 3 individuals in a thousand in a control group had some sort of an adverse outcome versus 4 out of a thousand in a group undergoing some treatment, the difference will be published in the medical literature with great excitement and intimations of its importance. In fact, of course, such small differences are almost certainly random noise and are in any rational calculus unimportant. And statistical significance is little help in determining the importance of a finding. Statistical significance simply tells you that the result was unlikely to be an effect of small sample size. But a statistically significant difference could have been due to any number of other randomly-present factors.

"The modern literature on hate crimes began with a remarkable 1933 book by Arthur Raper titled The Tragedy of Lynching. Raper assembled data on the number of lynchings each year in the South and on the price of an acre's yield of cotton. He calculated the correlation coefficient between the two series at -0.532. In other words, when the economy was doing well, the number of lynchings was lower.... In 2001, Donald Green, Laurence McFalls, and Jennifer Smith published a paper that demolished the alleged connection between economic conditions and lynchings in Raper's data. Raper had the misfortune of stopping his analysis in 1929. After the Great Depression hit, the price of cotton plummeted and economic conditions deteriorated, yet lynchings continued to fall. The correlation disappeared altogether when more years of data were added."

So we must be sure to base our conclusions on ALL the data. But in medical research, data selectivity and the "overlooking" of discordant research findings is epidemic.

The Truth About Ancel Keys. Keys was a brilliant man but his concentration on heart disease misled him. He was right that high fat intake predicted high rates of heart disease (though it was ANIMAL fat in particular that was the "culprit") but he overlooked that the same intake predicted LESS mortality from other causes. The same narrow vision led him to be the earliest prominent advocate of the "Mediterranean diet" hypothesis. It's true that Mediterraneans have less heart disease but they have more of other causes of death, so that Mediterranean countries do not have particularly long lifespans when compared with other developed countries. If there are any lessons about diet to be learned from lifespans, it is un-Mediterranean countries like Australia and the Nordic countries that one should look to.

The intellectual Roman Emperor Marcus Aurelius (AD 121-180) could have been speaking of the prevailing health "wisdom" of today when he said: "The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane."

Improbable events do happen at random -- as mathematician John Brignell notes rather tartly: "Consider, instead, my experiences in the village pub swindle. It is based on the weekly bonus ball in the National Lottery. It so happens that my birth date is 13, so that is the number I always choose. With a few occasional absences abroad I have paid my pound every week for a year and a half, but have never won. Some of my neighbours win frequently; one in three consecutive weeks. Furthermore, I always put in a pound for my wife for her birth date, which is 11. She has never won either. The probability of neither of these numbers coming up in that period is less than 5%, which for an epidemiologist is significant enough to publish a paper.

Kids are not shy anymore. They are "autistic". Autism is a real problem but the rise in its incidence seems likely to be the product of overdiagnosis -- the now common tendency to medicalize almost all problems.

One of the great pleasures in life is the first mouthful of cold beer on a hot day -- and the food Puritans can stick that wherever they like

NOTE: The archives provided by blogspot below are rather inconvenient. They break each month up into small bits. If you want to scan whole months at a time, the backup archives will suit better. See here or here